Production of cellulose derivative staple fiber yarns



Patented Oct. 3, 1939 PRODUCTION OF OELLULOSE DERIVATIVE STAPLE FIBER YARNS William Ivan Taylor, Spondon, near Derby, England, assignor to Celanese Corporation of America, a corporation of Delaware No Drawing. Application April 15, 1937, Serial No. 137,043. In Great Britain May 1, 1936 8 Claims.

This invention relates to improvements in the production of textile materials, and is more particularly concerned with the production of yarns having characteristics closely allied with those of natural fibers, and particularly wool, but consisting of .or containing cellulose derivatives.

In U. S. Patents Nos. 2,077,078 and 2,077,079, there are described processes for the direct con version of continuous filament yarns into yarns 10 containing staple fiber. These processes involve causing the bundle of continuous filaments to pass between two surfaces, one of which at least is a cutting surface moving at a speed different from that of the bundle, the other surface serving to press the bundle substantially at a point in its length against the cutting surface. The cutting surface may take the form of a fluted cutting roller as in U. S. Patent No. 2,077,079, or may be an endless cutting band as in U. S. Patent N0. 2,077,078, and the pressing surface may be a stationary surface or may be a surface, for example a roller, moving at substantially the same speed as the cutting roller or surface as in U. S. Patent No. 2,077,078. It is stated in the said specifications that the filaments contained in the basic' yarn may be filaments which are delustred cellulose derivative filaments obtained by subjecting celllulose acetate or other cellulose derivative materials to hot aqueous liquors or liquors containing thiocyanates or solvents for the cellulose derivative. By converting such a yarn into a staple fiber yarn by the processes of the prior specifications, a product is produced which has a subdued lustre, is crinkled to some extent by the delustring treatment and is .of staple fiber yarn. Hence it bears considerable resemblances to the ordinary staple fiber yarns of natural fibers.

I have now found that superior products, particularly as regards the amount of crinkle, may

um after the conversion of the continuous filament yarn into a yarn containing staple fiber, a-

higher degree of crinkle is imparted than is the case when the treatment with the hot aqueous liquors precedes the conversion of the yarn to a 55 yarn containing staple fiber.

be obtained by converting continuous filament If desired, the yarn to be treated in accordance with the combined process of the present invention may, before or after conversion into a yarn containing staplefiber, be subjected to any additional process designed to impart crinkle to the material, as for example a process in which the yarn either consisting of continuous filaments or already converted into a yarn containing sta-r ple fiber is subjected to a relatively high degree of twist, the twist set and the yarn finally untwisted. Such processes are described in U. S. Patents Nos. 2,089,198 and 2,089,199 and British Patent No. 464,981. By this means additional crinkle is imparted to theyarn over and above that due to the treatment with the hot aqueous media. Such a crinkling treatment may either precede or follow the treatment with the hot aqueous medium.

The material constituting the yarn may be cellulose acetate or any other organic derivative of cellulose, for example cellulose formate, 'propionate or butyrate, or other organic esters or mixed esters of cellulose, or ethyl or benzyl'cellulose or other cellulose ethers or mixed ethers of cellulose, or mixed ether-esters of cellulose. If desired, in the conversion of the continuous filament yarn into a yarn containing staple fiber, filaments of other kinds may be mixed with the cellulose derivative filaments and simultaneously converted into staple fiber, for example natural silk filaments, filaments of regenerated cellulose or the like. Further, an additional yarn may be doubled with the product delivered from the cutting device. Thus a continuous filament yarn which is light in denier as compared with the denier of the bundle or bundles to be cut may be fed to rollers designed to draw the yarn to be out between the cutting and presser surfaces, so as to proceed with the bundle or bundles of cut filaments to a twisting device in which both the yarn containing staple fiber and the additional yarn are doubled together. f

The direct conversion of continuous filament yarns to staple fiber yarns may be effected, according to this invention, by any of the processes described in U. S. Patents Nos. 2,077,078 and 2,077,079, referred to above.

As a result of the treatment according to the present invention, the cellulose derivative materials have a subdued lustre. If the lustre is required to be reduced still more, the process may be combined with a special delustring treatment. for example byincorporating white pigments into the materials either during the spinning process for producing, the original filaments, i, e. by incorporating the pigment in the spinning solution, or as an aftertreatment applied to the materials, such aftertreatment being applied at any convenient stage.

While the present invention contemplates the treatment by the combined process of directly converting a continuous filament yarn into a yarn containing staple fiber and subsequent treatment in the hot aqueous liquor of cellulose derivative yarn of any character, especially valuable results may be obtained by treating yarns containing filaments or fibers of fiat cross-section, such filamentsbeing preferably, of as high a filament denier as is compatible with obtaining satisfactory results in the operation of conversion of the yarn to yarn containing staple fibers.

' The filaments or fibers constituting the yarn may be wholly fiat in cross-section or may contain a substantial proportion of flats (as opposed to the bulbous type of cross-section), for exam- .ple more than 50% and preferably more than 70 or 80% of -fiats. It is found that the hot aqueous treatment imparts a much better crinkle to such materials than materials consisting wholly of filaments or fibers having a bulbous crosssection. The filaments or fibers of fiat crosssection may be produced by any convenient method. The most convenient method is to spin a cellulose derivative solution containing the cellulose'derivative in a concentration lower than the minimum required tb produce bulbous crosssection. In particular, in the case of a solution of cellulose acetate in acetone, a concentration of 24% or lower, down to say 20%, and especially a concentration about 22-23 produces a good variety of filament for the purpose of the present invention.

While the treatment with a hot aqueous medium may simply consist of a treatment in wet steam, it is preferred toemploy a boiling or almost boiling aqueous liquor. Such a liquor may contain a wetting agent, as for example a watersoluble soap or a sulphonated oil, for instance Monopol soap or Turkey red oil, or other sulphonated higher aliphatic compound, for instance a sulphonated higher fatty acid or a sulphonated higher fatty alcohol, or true sulphonic acids of the higher members of the aliphatic series. The 7 treatment may, for example, be a treatment at the boil for hourto 1 /2 hours in water containing a small proportion, e. g., up to 1 gram The treatment with a hot aqueous liquor may .be operated so as to exercise a control over the lustre of. the final product. A treatment of a cellulose acetate material with a boiling solution as described above produces a substantial reduction in lustre. A similar treatment with boiling water produces a much smaller reduction in lustre but still results in a product of substantially reduced lustre. If desired, saltsor sugars may be added to the aqueous liquor, for

' example in a concentration upto 10 or 20% so as to reduce the loss in'lustre occasioned by the hot aqueous treatment. Thus, for example,.

and obtain a product which has a very. good lustre and at the same-time, is well crinkled, or crimped. For further information relating to 1 these salts or sugars which have the effect of protecting the lustre of the material reference is made to U. S. Patents Nos. 1,765,581 and 1,- 808,061. If desired the treatment with a hot aqueous medium may take place under pressure so as to enable temperatures higher than 100 C. to be used. v

It is preferable in order to obtain a yarn of very woolly characteristics to finish with a doubled yarn having a light doubling twist which is reverse in direction to any twist in the constituent yarns. The twist, if any, in the constituent yarns should also be light. It is further very advantageous to have the product in this form before applying the treatment with the hot aqueous medium. This form of product may result directly from a twisting, setting and untwisting step. For example, two or three yarns having either no twist or each having a light degree of twist in the same direction may be twisted together with a relatively high degree of twist, the twist set, as for example by means of steam, and the doubled yarn then untwisted so as to leave in the final yarn a light doubling twist, reverse in direction to any original twist in the constituent yarns. Where, as is preferred,

the twisting, setting and untwisting operation comprises the insertion of false twist, the production of a doubled yarn of the character referred to will take place in a separate operation, and may either precede or follow the twisting, setting and untwisting operation.

Generally, by a light twist is meant a twist of not more than 5 turns per inch. A doubled yarns, each having say 0 or up to 1 to 2 turns per inch, and doubling them together with a doutwo doubling operations may be employed. Thus,

a number of single yarns each having 1 turn perinch or less may be doubled together with a doubling twist of 1 turn per inch in the same direction, and a number of yarns so doubled together with a doubling twist of 2 turns per' inch reverse in direction.

Similarly, a doubled'yarn having the above characteristics may be obtained directly during the step of converting continuous filament yarns to staple fiber yarns. continuous filament yarns having no twist or a For example, a number of a light twist in one direction may be converted into yarns containing staple fiber by the process of U. S. Patent-No.-2,07'7,079 and a number of such yarns travelling from this direct conversion process doubled together with a light twist,

reverse in direction to any on'ginal twist in the yarn.

The phrase direct conversion processfiused in this specification and in the following claims means that the yarn does not at any stage from the continuous filament yarn to the yarn containing staple fiber lose its continuity, and the expression, therefore, does not include a process in which the filaments are cut to staple length and the staple fibers subsequently spun into staple fiber yarn. a

. Having described my invention what I desire to secure by Letters Patent is:

1. Process for the production of improvedstaple fiber yarns, which comprises twisting continuous filament yarns which have a basis of organic derivatives of cellulose, and which contain a high proportion of filaments of fiat cross section setting the twist therein and untwisting such yarns, converting the yarns into staple fiber yarns by a direct conversion process, and thereafter subjecting the yarns to treatment with a bath of hot aqueous liquid maintained at a temperature of the order of the boiling point of such liquid.

2. Process for the production of improved staple fiber yarns, which comprises twisting continuous filament yarns which have a basis of cellulose acetate and which contain a high proportion of filaments of fiat cross-section, setting the twist therein and untwisting such yarns, converting the yarns into staple fiber yarns by a direct conversion process, and thereafter subjecting the yarns to treatment with a bath of hot aqueous liquid maintained at a temperature of the order of the boiling point of such liquid.

3. Process for the production of improved staple fiber yarns, which comprises converting to staple fiber yarns by a direct conversion process continuous filament yarns which have a basis of organic derivatives of cellulose and which contain a high proportion of filaments of flat cross-section, thereafter twisting the yarns, setting the twist therein and untwisting the yarns, and then subjecting the yarns to treatment with a bath of hot aqueous liquid maintained at a temperature of the order of the boiling point of such liquid.

4. Process for the production of improved staple fiber yarns, which comprises converting to staple fiber yarns by a direct conversion process continuous filament yarns which have a basis of cellulose acetate and which contain a high proportion of filaments of fiat cross-section, thereafter twisting the yarns, setting the twist therein and untwisting the yarns, and then subjecting theyarns to treatment with a bath of hot aqueous liquid maintained at a temperature of the order of the boiling point of such liquid.

5. Process for the production of improved staple fiber yarns, which comprises twisting continuous filament yarns which have a basis of organic derivatives of cellulose and which contain a high proportion of filaments of flat cross-section, setting the twist therein and untwisting such yarns,

converting the yarns into staple fiber yarns by a direct conversion process, and thereafter subjecting the yarns to treatment with a bath of hot aqueous liquid maintained at a temperature of the order of the boiling point of such liquid, said bath containing a sugar.

6. Process for the production of improved staple fiber yarns, which comprises twisting continuous filament yarns which have a basis of cellulose acetate and which contain a high proportion of filaments of fiat cross-section, setting the twist therein and untwisting such yarns, converting the yarns into staple fiber yarns by a direct conversion process, and thereafter subjecting the yarns to treatment with a bath of hot aqueous liquid maintained at a temperature of the order of the boiling point of such liquid, said bath containing a sugar.

'7. Process for the production of improved staple fiber yarns, which comprises converting to staple fiber yarns by a direct conversion process continuous filament yarns which have a basis of organic derivatives of cellulose and which contain a high proportion of filaments of fiat cross-section, doubling together a number of such yarns having little or no twist by a doubling operation involving applying a light twist reverse in direction to any initial twist in the yarns, and thereafter subjecting the doubled yarns to treatment with a bath of hot aqueous liquid maintained at a temperature of the order of the boiling point of such liquid.

8. Process for the production of improved staple fiber yarns, which comprises converting to staple fiber yarns by a direct conversion process continuous filament yarns which have a basis of cellulose acetate and which contain a high proportion of filaments of fiat cross-section, doubling together a number of such yarns having little or no twist by a doubling operation involving applying a light twist reverse in direction to any initial twist in the yarns, and thereafter. subjecting the doubled yarns to treatment with a bath of hot aqueous liquid maintained at a temperature of the order of the boiling point of such liquid.

WILLIAM IVAN TAYLOR. 

